Lateral downslope transport and tentative sedimentary organic carbon box model in the southern Yap Trench,western Pacific Ocean  

作　　者：Dong Li Jun Zhao Chenggang Liu Jianming Pan Ji Hu 

机构地区：[1]Key Laboratory of Marine Ecosystem Dynamics,Second Institute of Oceanography,Ministry of Natural Resources,Hangzhou,310012,China

出　　处：《Acta Oceanologica Sinica》2023年第1期61-74,共14页海洋学报（英文版）

基　　金：The Scientific Research Fund of the Second Institute of Oceanography under contract Nos JG2011 and JG1516;the National Natural Science Foundation of China under contract No.41606090;the National Basic Research Program(973 Program)of China under contract No.2015CB755904.

摘　　要：Sediment collapse and subsequent lateral downslope migration play important roles in shaping the habitats and regulating sedimentary organic carbon(SOC)cycling in hadal trenches.In this study,three sediment cores were collected using a human-occupied vehicle across the axis of the southern Yap Trench(SYT).The total organic carbon(TOC)and total nitrogen(TN)contents,δ13C,radiocarbon ages,specific surface areas,and grain size compositions of sediments from three cores were measured.We explored the influence of the lateral downslope transport on the dispersal of the sediments and established a tentative box model for the SOC balance.In the SYT,the surface TOC content decreased with water depth and was decoupled by the funneling effect of the V-shaped hadal trench.However,the sedimentation(0.0025 cm/a)and SOC accumulation rates(∼0.038 g/(m^(2)·a)(in terms of OC))were approximately 50%higher in the deeper hadal region than in the abyssal region(0.0016 cm/a and∼0.026 g/(m^(2)·a)(in terms of OC),respectively),indicating the occurrence of lateral downslope transport.The fluctuating variations in the prokaryotic abundances and the SOC accumulation rate suggest the periodic input of surficial sediments from the shallow region.The similar average TOC(0.31%–0.38%),TN(0.06%–0.07%)contents,and SOC compositions(terrestrial OC(11%–18%),marine phytoplanktonic OC(45%–53%),and microbial OC(32%–44%))of the three sites indicate that the lateral downslope transport has a significant mixing effect on the SOC composition.The output fluxes of the laterally transported SOC(0.44–0.56 g/(m^(2)·a)(in terms of OC))contributed approximately(47%–73%)of the total SOC input,and this proportion increased with water depth.The results of this study demonstrate the importance of lateral downslope transport in the spatial distribution and development of biomes.

关 键 词：southern Yap Trench sedimentary organic carbon cycling lateral downslope transport diluting effect box model 

分 类 号：P736.41[天文地球—海洋地质]